It is known that each step of a person moving on the ground involves a first phase in which one or the other of his feet first hits the ground with its heel, at a certain speed and with a certain weight. In the following phase of the same step, the impact of the force due, at least in part, to the action of body weight on the ground, and exerted in the first phase of the step on the heel, shifts forward towards the toes of the same foot. In the last phase of the step, when the bodyweight lies on the ball of the foot, the muscles of the leg provide an impulse to the foot to lift it from the ground. The more vigorous this impulse is, the easier or the greater is the velocity of locomotion of a person; the impulse is thus particularly indicative of a slow or fast motion.
It therefore seemed interesting to capture, at least in part, the energy which is lost in the first phase of the step of each foot, that is at the moment when the heel of a person hits the ground, and to return it in the sense of reutilization of this energy, at least in part, during the last phase of the step. Thus it is possible to allow a person advancing with more or less speed on the ground, to move more easily, in as much as the impulse provided by the muscles of each leg can be supplemented by the impulse produced by the device described in the present invention, and which, at the moment the foot of a person is about to leave the ground, releases a certain quantity of energy, which had been stored during the first phase of the step.